1. Field of the Invention
The invention relates to a contactless power transferring coil unit for transferring power by a contactless method using electromagnetic induction such as when charging secondary cells incorporated in a small and slim mobile terminal (for example, a mobile-phone unit). The invention further relates to a mobile terminal in which the contactless power transferring coil unit is incorporated, a power transmitting apparatus that transfers power to a mobile terminal or the like using a contactless power transferring coil, and a contactless power transferring system including such devices.
2. Description of the Related Art
An existing system is known for transferring charging power, which is used to charge secondary cells incorporated in a mobile terminal for example, via contactless power transferring coils using magnetic induction.
Japanese Unexamined Patent Application Publication No. 2006-42519 (see FIG. 2 and FIG. 3) discloses the use of a flat coil, which is formed by winding a wire which is composed of a solid wire or a twisted wire with an insulating layer on the surface thereof into a spiral on a substantially flat plane, as a contactless power transferring coil installed in a mobile terminal, such as a mobile-phone unit, that may need to be made slim. This publication also discloses that a magnetic sheet for suppressing unneeded radiation due to the magnetic fields produced from a power-transmitting flat coil and a power-receiving flat coil when such coils are disposed facing one another is provided on the opposite surface of each coil to the facing surfaces so as to entirely cover such opposite surfaces.